1. Field of the Invention
The invention relates to a strain pick-up for testing of materials, wherein two tapping points which are applied to a test piece are mounted on rigid elbow members, the spacing of which can be changed within limits.
2. Description of the Prior Art
There are known strain pick-ups in which the two tapping points are attached to rigid elbow members which form the ends of a casing and are displaceable relative to one another. In order to convert the magnitude of displacement into electrical analog data, there is provided induction equipment in which a magnetic core is located symmetrically between two coils. The magnetic core, which is coupled to one of the two displaceable ends, is displaced relative to the coils upon a change in the distance between the tapping points, whereby the symmetry of a measuring bridge is disturbed. Such strain pick-ups are expensive and bulky, and are relatively heavy in weight because of the coils and cores. Several such strain pick-ups may be employed at the same time, but must always be a definite minimum distance apart. Measurements of strain distributions and strain gradients within the limits of stress concentrations are very difficult with the known instruments.